Emergency pump system with duplicate fluid lines

ABSTRACT

A hydraulic power brake and steering system for an automobile in which a primary engine driven pump provides fluid power for normal requirements, and an auxiliary electric motor driven pump provides fluid power in event of failure of the primary system. The system includes flow sensing means to determine when the primary system has failed, and also includes duplicate sets of hydraulic lines and pump reservoirs and a pair of shuttle valves for switching the flow from one set of lines and reservoir to the other depending upon which pump is providing fluid power.

O Unlted States Patent 1 [111 3,733,817 MacDuff 51 May 22, 1973 54]EMERGENCY PUMP SYSTEM WITH 2,896,733 7 1959 Rockwell ..60/54.5 PDUPLICATE FLUID LINES 3,088,284 /1963 Aaron ..60/52 S 2,954,671 10 1960K t ..60 52 S [751 Invent: smlley Mum, Daymna, 3,556,242 1il97l 0271256.... ..eoisz s 73 Assignee: The Bendix Corporation South 3,579,9845/1971 R0hde..... ....60/52 S Bend, mi 3,590,689 7/l97l Brewer ..60/52 SFiledi J 1971 Primary Examiner-Martin P. Schwadron 21 APPL NOJ 15 721Assistant Examiner-A. M Zupcic Attorney-Ken C. Decker et al.

[52] US. Cl ..60/405, /545 P, ISO/79.2 R [57] ABSTRACT [51] Int. Cl. ..1..FlSb 15/18, FlSb 7/00 [58] Field of Search ..60/54.5 P, 54.6 P, Ahydraulw Power brake and Steering System for an 0 545 R 52 S, 52 S;137/112; 180/792 R; automobile in which a primary engine driven pump 3034 A 10 2 provides fluid power for normal requirements, and an auxiliaryelectric motor driven pump provides fluid [56] R f r Cit d power inevent of failure of the primary system. The system includes flow sensingmeans to determine when UNITED STATES PATENTS the primary system hasfailed, and also includes 2,811,979 11/1957 Presnell ..303/84 AduPlicate Sets 0f hydraulic and P reservoirs 2,394,343 2/1946 v h and apair of shuttle valves for switching the flow from 3,280,557 10/1966Sattavara.... one set of lines and reservoir to the other depending3,633,363 1/1972 Larsen upon which pump is providing fluid power.3,131,538 5/1964 Schultz et al... 3,434,282 3/1969 Shelhart ..60/52 S 6Claims, 1 Drawing Figure 60 Hill-- I as 54 I 6 /9 I ine 4 I I0 H 4!? mav v v 01&IIt'0 ii/l l l il l"| gefilalgfiilfi l g ,1. 7 74 0/11; 1 7p.1- .I l- 25% 1 hflW/i PATENIELI-ZKYQZIGYS 3,733,817

INVENTOR. STA/V1.5) I. MACDUFF ATTORNEY EMERGENCY PUMP SYSTEM WITHDUPLICATE FLUID LINES SUMMARY OF THE INVENTION This invention relates toan emergency pump system to be used in an automotive vehicle equippedwith hydraulic power booster devices such as a conventional open centerhydraulic steering gear and a series parallel hydraulic brake booster. Abrake booster of this kind is described in U. S. Pat. application Ser.No. 793,923, filed Jan. 16, 1969, having in common with this applicationthe same assignee. Such systems normally are provided with fluid powerfrom a pump driven by the engine of the vehicle.

An object of the invention is to provide fluid power to the steeringgear and brake booster continuously in the event of failure of thenormal or primary supply from the engine driven pump. This isaccomplished by providing an emergency or auxiliary pump driven by meansother than the engine, such as by an electric motor receiving power fromthe vehicle electrical system. The electric motor is arranged to startin response to signals received from a flow sensing means installed inthe primary fluid circuit. The flow sensing means determines whetherfluid is flowing in the primary circuit.

At any time that fluid is not flowing in the primary circuit and thevehicle ignition switch is closed, the flow sensing means starts theelectric motor drive pump to supply a limited quantity of fluid to thesystem.

A feature of the invention is the provision of duplicate or redundantfluid lines and pump reservoirs, and shuttle valves for switching theflow from one set of lines to the other automatically in dependence uponwhether the primary pump or the emergency pump is supplying fluid to thesystem. Thus, another object of the invention is to provide an emergencyor auxiliary pump system which provides protection against a rupturedhose or tube in the primary system.

BRIEF DESCRIPTION OF THE DRAWING The sole FIGURE of the drawing is aschematic view of a braking system made pursuant to the teachings of myinvention with the shuttle valves used therein illustrated in section.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, there isshown schematically a hydraulic system for an automotive vehicleincluding an engine driven pump having a reservoir 12, a hydraulic brakebooster 14 adapted to operate a conventional dual master cylinder 16,and a hydraulic power steering gear indicated generally by the numeral18. The pump 10 is provided with a conventional relief valve 19connected to return fluid to the reservoir 12 if system pressure limitsare exceeded. The brake booster 14 is of the type disclosed inaforementioned U. S. Pat. application Ser. No. 793,923, filed Jan. 16,1969, and is actuated by a brake pedal 20 connected to an actuatingplunger 22. The master cylinder 16 is connected by suitable conduits 24and 26 to front disc brakes 28 and rear drum brakes 30, respectively.The hydraulic power steering gear 18 has a valve 32 of the usual opencenter type operated by a steering wheel 34. The steering gear 18 has anoutput shaft 36 on which a pitman arm 38 is mounted. A linkage 40 isconnected to steering arms 42 attached to spindles of front wheels 44.

As an important feature of the invention,-the system also includes anauxiliary pump 46, having a reservoir 48, and driven by an electricmotor 50. The auxiliary pump 46 is provided with a conventional reliefvalve 51 connected to return fluid to the reservoir 48 if systempressure limits are exceeded. Since the'auxiliary pump motor 50, bypractical necessity is limited in its power output, the relief valve 51is preferably set to operate at a pressure substantially less than thepressure at which the primary system relief valve is set. The electricmotor 50 is connected in a circuit 52 including the vehicle electricsystem battery 54, the ignition switch 56 and a switch 58 which is partof a flow sensing means 60. A small light 62 is connected across theterminals of the motor 50.

The brake booster 14 and the power steering valve 32 are each containedin cast metal housings 64 and 66 respectively, which are formed withelongated bores 68 and 168 respectively; containing shuttle valveplungers 70 and 170, respectively. The bores 68 and 168 and the plungers70 and 170 constitute shuttle valves for the power brake booster 14 andthe power steeringgear 18. The shuttle valves, which constitute animportant feature of the invention, will be designated generally by thenumerals 72 and 172. Since the shuttle valves are identical inconstruction and function, the parts of the shuttle valve 172 which arethe same as parts of the shuttle valve 72 will be designated by the samenumerals increased by 100. In further description, only the shuttlevalve 72 will be referred to but, by adding 100 to the numerals, thedescription can be read in reference to the shuttle valve 172.

The bore 68 of the shuttle valve 72 is formed at its rightward end (asseen in the drawing) with an auxiliary circuit inlet port 74 and at itsleftward end with a primary circuit inlet port 76. Intermediate theseports from right to left are the following elements: an annular groovecontaining an O-ring 78; an annular groove 80 communicating by a lateralpassage 82 with an auxiliary circuit outlet port 84; another O-ring 86;an annular groove 88 communicating by a lateral passage 90 with anannular groove 92 of a bore 94 which, with a plunger 96, constitutes thebrake booster valve desig nated generally by the numeral 98; anotherO-ring 100; an annular groove 102 communicating by a lateral passage 104with a primary circuit outlet port 106; two more O-rings 108 and 110spaced apart a predetermined distance; an annular groove 112 connectingby a lateral passage 114 to an annular groove 116 of the bore 94 of thebrake booster valve 98; and an O-ring 118. The plunger 70, which isillustrated in its leftmost position, is formed from right to left withthe following elements: a wide groove 120 forming a communicationbetween the annular groove 80 and the annular groove 88; a similar widegroove 122 positioned between the O-rings 100 and 108 and communicatingwith the annular groove 102; and a narrow groove 124 aligned with theannular groove 112 and thereby communicating by means of the lateralpassage 114 with the annular groove 116 of the brake booster valve 98.The groove 124 also communicates with the auxiliary circuit inlet port74 through a drilled central hole 126 and interconnecting cross-drilledholes 128 in the plunger 70.

The brake booster valve plunger 96 is formed with an annular groove 130which overlaps the grooves 92 and 116 in the bore 94 when the brakepedal is in the released position. Thus it will be seen that there isfree communication between the grooves 92 and 116, and therefore,between the grooves 88 and 112 which are connected to the grooves 92 and116 by lateral passages 90 and 114. The lateral passage 114 constitutesthe inlet connection of the brake booster valve 98 and the lateralpassage 90 constitutes the outlet connection of the brake booster valve98. Detailed description of the brake booster valve 98 and its operationwill not be included in this specification as it may be obtained fromthe above-mentioned U. S. Pat. application Ser. No. 793,923, filed Jan.16, 1969. Similarly, since the hydraulic power steering gear valve 32 isof the open center type, whose operating characteristics are well knownin the art, it will be understood that, when the steering gear is notbeing operated there is free communication between lateral passages 214and 190, and therefore, between annular grooves 212 and 188.

The outlet of the primary pump is connected to the primary circuit-inletport 76 of the shuttle valve 72 by a conduit or line 132. The primarycircuit outlet port 106 is connected by a line 134 to the primarycircuit inlet port 176 of the steering gear shuttle valve 172. Theprimary circuit outlet port 206 is connected by a line 136 to thereservoir 12 of the primary pump 10. The flow sensing means 60 ispositioned in this line 136 near the reservoir 12. It should be notedhere that the discharge of the relief valve 19 is connected to the line136 ahead of the flow sensing means. Flow sensing devices which operateswitches are well known in the hydraulic art an it is not considerednecessary to illustrate the device 60 in detail or describe it otherwisethan by its desired function. The auxiliary pump 46 is connected by aline 138 to the auxiliary circuit inlet port 74 of the shuttle valve 72.The auxiliary circuit outlet port 84 of the shuttle valve 72 isconnected by a line 140 to the auxiliary circuit inlet port 174 of theshuttle valve 172. The auxiliary circuit outlet port 184 of the shuttlevalve 172 is connected by a line 142 to the reservoir 48 of theauxiliary pump 46.

It should be understood that the lines 132, 134 and 136 may consist ofseveral pieces of metal tubing and flexible hose of suitable typesjoined together by various fittings which may be threaded or clampedtogether. The lines 132, 134 and 136 are the same lines that would existin a conventional automobile equipped with hydraulic power brakes andsteering. These lines are subject to failures which result'in loss ofpressure and of fluid, causing the brake and steering systems to revertto heir conventional manual modes of operation. When this occurs,substantial increases in effort are required of the driver to obtain thedesired function. These increases in effort are confusing to drivers,and, in the case of younger drivers and small women, may be beyond thestrength of the drivers, causing the defective vehicle to be unsafe intheir hands. The addition of the shuttlevalves 72 and 172, the auxiliarypump 46 and reservoir 48, and a complete parallel system of lines 138,140 and 142 protect such drivers and render the operation of thevehicles so equipped safe and free of difficulties, as will be apparentin the following description of the operation of the invention.

OPERATION OF THE INVENTION In the illustration, the plungers 70 and 170*of the shuttle valves 72 and 172 are in their leftmost position, and itmay be assumed that the vehicle engine is not running because the flowsensing switch 58 of the flow sensing means 60 is shown to be closedindicating that there is no flow in the line 136. Now, if the drivercloses the ignition switch 56 in preparation for starting the engine,the electrical circuit 52 will be completed and the auxiliary pump motor50 will start. The light 62, which is mounted on the instrument panel ofthe vehicle, will come on to indicate that the auxiliary system isworking. The motor 50 drives the pump 46 which draws fluid from thereservoir 48 and discharges it into the line 138. The fluid flowing inthe line 138 enters the shuttle valve 72 through the port 74 and flowsthrough the drilled passages 126 and 128 into the groove 124. Since thegroove 124 is in communication with the groove 112, fluid flows fromthere through the passage 114 to the brake valve 98. The fluid passesthrough the annular grooves 116 and 92 of the brake valve bore 94 andthe annular groove 130 of the brake valve plunger 96 and re-enters theshuttle valve 72 by means of the lateral passage leading to the annulargroove 88. Since the groove of the shuttle valve plunger 70 overlapsboth annular grooves 88 and 80, the fluid continues into groove 80, andfrom there, flows through the lateral passage 82 to the auxiliarycircuit outlet port 84. Then the fluid flows through the line to theauxiliary circuit inlet 174 of the steering gear shuttle valve 172. Thefluid follows the same path through this shuttle valve 172 as has justbeen described, passing from the lateral passage 214 through thesteering valve 32 to the lateral passage and then to the auxiliaryoutlet port 184. From the auxiliary outlet port 184 the fluid returns tothe reservoir 48 through the line 142. Since the hydraulic fluid isvirtually incompressible, it will be understood that the flow occurs inall areas substantially simultaneously and continues as long as themotor 50 is running. If the driver needs to operate the steering gear 18or the brake booster 14 before the engine is started, they will functionwith the same ease and effectiveness as would be the case if the enginewere running. However, because of the limitation of flow and pressure inthe auxiliary system, full emergency stops and turns can not be madewithout some increased effort. In actual practice, it is found that needfor maximum performance very rarely coincides with periods when thedriver is relying on the emergency system.

If the driver now proceeds to start the engine, the primary system pump10 will start to operate. The pump 10 takes fluid from the reservoir 12and discharges it under pressure to the line 132. Due to the position ofthe shuttle valve plunger 70 fluid entering the primary circuit inletport 76 is blocked. The pressure developed by the pump 10 will increaseuntil the relief valve 19 operates, permitting the fluid to flow intothe line 136 and back to the reservoir 12 through the flow sensing means60. The flow through the flow sensing means 60 causes the switch 58 toopen, stopping the auxiliary pump motor 50. At the same time theincreased pressure of the pump 10 acting on the left end of the plunger70 exerts a force on the plunger urging it to the right. This force willbe greater than any force that may be exerted on the right hand end ofthe plunger 70 by pressure from the auxiliary pump 46, because, aspreviously stated, the auxiliary pump relief valve 51 is set at a lowerpressure than the relief valve 19 of the primary pump 10. Consequently,the plunger 70 will be moved instantly to its rightmost position,causing changes in the relative positions of the grooves and passages ofthe shuttle valve 72 as follows: the left end of the plunger 70 movesinto the annular groove 112, permitting fluid from the primary circuitinlet port 76 to pass into the groove 112 and then into the lateralpassage 114 leading to the brake booster valve 98; the narrow groove124'of the plunger 70 moves into a position between the O-rings 110 and108, thereby sealing off further flow of fluid into the auxiliarycircuit inlet port 74; the wide groove 122 of the plunger 70 moves to aposition where it overlaps both annular grooves 102 and 88 of the bore68 so that fluid leaving the power brake booster valve via the lateralpassage 90 now flows to the primary circuit outlet port 106 and the line134; and the wide groove 120 of the plunger 70 moves to a positionbetween the O-rings 86 and 78, thereby sealing off exit of fluid to theauxiliary circuit outlet port 84. The fluid that is now attempting toflow through the line 134 is initially blocked by the leftward positionof the plunger 170 of the steering gear shuttle valve 172. The resultingpressure in the line 134 shifts the plunger 170 in the same way as hasjust been described relative to the plunger 70. With the plunger 170 inits rightmost position, the flow to the steering valve 32 is from theprimary circuit inlet port 176 to the primary circuit outlet port 206,and flow in the auxiliary circuit is blocked. Now the power brakebooster l4 and the steering gear 18 will operate normally and at theirfull capacity.

If the engine stalls while the vehicle is in motion, or if a hose ortube ruptures, or if ajoint, fitting, seal or connection leaks, flow inthe line 136 ceases. The flow sensing means 60 then closes the switch 58to start the motor 50 which operates the pump 46. Since the primarysystem is without flow, and consequently is also without pressure, theauxiliary system will develop enough pressure to shift the plungers 70and 170 instantly back to their leftmost positions. This restores theflow paths first described so that operation of the brakes and steeringcan be carried on using power from the auxiliary circuit. It should benoted that the several O-rings provide positive sealing of the plungers70 and 170 and the bores 68 and 168 to segregate the two systems fromeach other, so that a failure in one of the systems does not affect theother system. The warning light 62 informs the driver when the vehicleis operating on the auxiliary system so that repairs can be made to theprimary system when needed. Failure of the warning light to come onduring the period when the ignition switch is closed but the engine hasnot started will indicate need of repair of the auxiliary system.

I claim:

1. In an automotive vehicle equipped with power steering and power brakedevices normally supplied pressurized fluid by a primary fluid circuitincluding an engine driven pump, an emergency pump system comprising:

an auxiliary circuit including an auxiliary pump having drive meansother than the engine;

first valve means having first and second inlets connected to receivepressurized output fluid flow from said engine driven and auxiliarypumps, respectively, and first and second outlets adapted to becommunicated with said first and second inlets, respectively;

second valve means having third and fourth inlets connected to saidfirst and second outlets, respectively, and third and fourth outletsadapted to be communicated with said third and fourth inlets,respectively;

first passage means connecting said third outlet with the inlet of saidengine driven pump;

second passage means connecting said fourth outlet with the inlet ofsaid auxiliary pump;

said first valve means being responsive to the pressure differentialbetween said first and second inlets and having a first position inresponse to said first inlet pressure exceeding said second inletpressure whereby communication between said first inlet and said firstoutlet is established and a second position in response to said secondinlet pressure exceeding said first inlet pressure whereby communicationbetween said second inlet and said second outlet is established;

said second valve means being actuated in response to pressurization ofsaid first outlet port to a first position whereby said third inlet portis communi cated with said third outlet and actuated in response topressurization of said second outlet port to a second position wherebysaid fourth inlet is communicated with said fourth outlet;

said first and second valve means being provided with fluid passagemeans connecting the same with said power brake mechanism and said powersteering mechanism, respectively, whereby both of the latter mechanismsare supplied pressurized fluid from one of said primary and auxiliarycircuits depending upon the position of said first valve means; and

flow responsive means operatively connected to said primary circuit forsensing flow therethrough and operatively connected to said auxiliarypump for rendering said auxiliary pump inoperative in response to apredetermined flow through said primary fluid circuit, said auxiliarypump becoming operative in the event said predetermined flow throughsaid primary circuit is not attained.

2. The invention of claim 1 in which the engine driven pump and theauxiliary pump are provided with separate fluid reservoirs.

3. The invention of claim 1 in which the auxiliary pump is driven by abattery powered electric motor having an electrical control circuitincluding first switch means actuated by said flow responsive means.

4. The invention of claim 1 wherein:

said first and second valve means each include a casing having a bore;

a valve member having a plurality of spaced apart land portions slidablycarried in said bore and first and second end portions exposed to saidfirst and second inlets, respectively;

said first end portion adapted to seat against said associated first andthird inlets to block flow therethrough and against said associatedsecond and 7 s 6. The invention of claim 1 and further including: iarypump with said second passage means; third Passage means mcludmg a firstfluid Pmssure said second fluid pressure relief valve operative torelief valve connecting the outlet of said engine driven pump with saidfirst passage means; fourth passage means including a second fluid pres-5 Pressure rehef Valvesure relief valve connecting the outlet of saidauxilopen at a lower fluid pressure than said first fluid

1. In an automotive vehicle equipped with power steering and power brakedevices normally supplied pressurized fluid by a primary fluid circuitincluding an engine driven pump, an emergency pump system comprising: anauxiliary circuit including an auxiliary pump having drive means otherthan the engine; first valve means having first and second inletsconnected to receive pressurized output fluid flow from said enginedriven and auxiliary pumps, respectively, and first and second outletsadapted to be communicated with said first and second inlets,respectively; second valve means having third and fourth inletsconnected to said first and second outlets, respectively, and third andfourth outlets adapted to be communicated with said third and fourthinlets, respectively; first passage means connecting said third outletwith the inlet of said engine driven pump; second passage meansconnecting said fourth outlet with the inlet of said auxiliary pump;said first valve means being responsive to the pressure differentialbetween said first and second inlets and having a first position inresponse to said first inlet pressure exceeding said second inletpressure whereby communication between said first inlet and said firstoutlet is established and a second position in response to said secondinlet pressure exceeding said first inlet pressure whereby communicationbetween said second inlet and said second outlet is established; saidsecond valve means being actuated in response to pressurization of saidfirst outlet port to a first position whereby said third inlet port iscommunicated with said third outlet and actuated in response topressurization of said second outlet port to a second position wherebysaid fourth inlet is communicated with said fourth outlet; said firstand second valve means being prOvided with fluid passage meansconnecting the same with said power brake mechanism and said powersteering mechanism, respectively, whereby both of the latter mechanismsare supplied pressurized fluid from one of said primary and auxiliarycircuits depending upon the position of said first valve means; and flowresponsive means operatively connected to said primary circuit forsensing flow therethrough and operatively connected to said auxiliarypump for rendering said auxiliary pump inoperative in response to apredetermined flow through said primary fluid circuit, said auxiliarypump becoming operative in the event said predetermined flow throughsaid primary circuit is not attained.
 2. The invention of claim 1 inwhich the engine driven pump and the auxiliary pump are provided withseparate fluid reservoirs.
 3. The invention of claim 1 in which theauxiliary pump is driven by a battery powered electric motor having anelectrical control circuit including first switch means actuated by saidflow responsive means.
 4. The invention of claim 1 wherein: said firstand second valve means each include a casing having a bore; a valvemember having a plurality of spaced apart land portions slidably carriedin said bore and first and second end portions exposed to said first andsecond inlets, respectively; said first end portion adapted to seatagainst said associated first and third inlets to block flowtherethrough and against said associated second and fourth inlets toblock flow therethrough depending upon the position of said valve meansassociated therewith.
 5. The invention of claim 3 wherein vehicle engineignition switch means is connected in said electrical control circuit inseries relationship with said first switch means to cause energizationof said electric motor in response to closing of said first switch meansand said ignition switch means and de-energization of said electricmotor in response to opening of one of said first switch means andignition switch means.
 6. The invention of claim 1 and furtherincluding: third passage means including a first fluid pressure reliefvalve connecting the outlet of said engine driven pump with said firstpassage means; fourth passage means including a second fluid pressurerelief valve connecting the outlet of said auxiliary pump with saidsecond passage means; said second fluid pressure relief valve operativeto open at a lower fluid pressure than said first fluid pressure reliefvalve.